PXN20RM Datasheet, PDF (1247/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Nexus Development Interface (NDI)
Misaligned accesses are NOT supported in the e200z0 Nexus2+ module.
36.7.9.5.1 Single Write Access
1. Initialize the read/write access address register (RWA) through the access method outlined in
Section 36.7.8, Nexus2+ Register Access via JTAG / OnCE using the Nexus register index of 0x9
(see Table 36-48). Configure as follows:
– Write Address  0xnnnn_nnnn (write address)
2. Initialize the read/write access control/status register (RWCS) through the access method outlined
in Section 36.7.8, Nexus2+ Register Access via JTAG / OnCE, using the Nexus Register Index of
0x7(see Table 36-48). Configure the bits as follows:
– Access Control RWCS[AC]  0b1 (to indicate start access)
– Map Select RWCS[MAP]  0b000 (primary memory map)
– Access Priority RWCS[PR]  0b00 (lowest priority)
– Read/Write RWCS[RW]  0b1 (write access)
– Word Size RWCS[SZ]  0b0xx (32-bit, 16-bit, 8-bit)
– Access Count RWCS[CNT]  0x0000 or 0x0001 (single access)
NOTE
Access count RWCS[CNT] of 0x0000 or 0x0001 performs a single access.
3. Initialize the read/write access data register (RWD) through the access method outlined in
Section 36.7.8, Nexus2+ Register Access via JTAG / OnCE, using the Nexus register index of 0xA
(see Table 36-48). Configure as follows:
– Write Data  0xnnnn_nnnn (write data)
4. The Nexus2+ module then arbitrates for the system bus and transfer the data value from the data
buffer RWD register to the memory mapped address in the read/write access address register
(RWA). When the access has completed without error (ERR = 0), Nexus2+ clears the DV bit in the
RWCS register. This indicates that the device is ready for the next access.
NOTE
The DV and ERR bits within the RWCS provide read/write access status to
the external development tool.
36.7.9.5.2 Block Write Access
1. For a non-burst block write access, follow Steps 1, 2, and 3 outlined in Section 36.7.9.5.1, Single
Write Access to initialize the registers, but using a value greater than one (0x1) for the
RWCS[CNT] field.
2. The Nexus2+ module then arbitrates for the system bus and transfer the first data value from the
RWD register to the memory mapped address in the read/write access address register (RWA).
When the transfer has completed without error (ERR = 0), the address from the RWA register is
incremented to the next word size (specified in the SZ field) and the number from the CNT field is
decremented.
Freescale Semiconductor
PXN20 Microcontroller Reference Manual, Rev. 1
36-97